(1) Field of the Invention
The invention relates to a book shaping and pressing machine comprising a plurality of uniformly spaced pressing appliances which are propelled along an endless path, each of these pressing appliances possessing a pair of pressing plates which face each other across a gap that can be varied, their function being to exert pressure on the pages of a book, this pressure being generated through the agency of spring elements, the machine further comprising heated joint-forming appliances which are installed on the pressing appliances, each of these joint-forming appliances possessing a pair of joint-forming rails which face each other across a gap that can be varied, their function being to form the book cover joints.
(2) Description of the Prior Art
In the manufacture of books on a commercial scale, the final operations performed on a book take place on a shaping and pressing machine, these being the operations in which the book cover joints are formed and the book is pressed over its entire area.
Both these operations are performed immediately after the casing-in operation, in which the book block is fitted into the book cover, and they not only endow the book with its aesthetically pleasing shape, but are the operations which primarily decide the quality of the book.
It is common knowledge that water-soluble adhesives are utilized in the casing-in operation, in which the book block is fitted into the book cover, and pressing the book causes the water component of the adhesive to migrate into the book cover and end leaves during the adhesive-setting process, so as to evaporate there. The function of a book shaping and pressing machine is to cause the adhesive to set within an extremely short period of time, this being accomplished by means of the pressing devices and requiring the application of very high pressing forces via pressing plates. The application of pressure is accompanied by smoothing of the materials through which moisture has penetrated as a result of the application of adhesive, the purpose of this smoothing being to keep these materials free of blisters and creases. The book cover joints are formed in the book-shaping device of the book shaping and pressing machine concurrently with the pressing operation. The formation of these cover joints is accomplished by means of heated profiled tools which act on the book cover surfacing material between the inserted spine and the cover boards. These profiled tools are often called "joint burn-in rails".
These profiled tools are intended to bring about thorough warming of the surfacing material, and consequently to render it more deformable in order to produce a durable joint-hinge profile, and this thorough warming is also desired in order to produce a strong adhesive bond between the book block and book cover in the region of the joint hinges. Adequate heated-tool contact time is decisively important with regard both to forming the joint hinges and to the setting of the adhesive that is applied relatively thickly in the joint region during the casing-in operation. A book shaping and pressing machine that operates on a succession of books is disclosed in German Patent 1,207,334, this machine comprising a rotary head that is movable about a vertical axis, the periphery of this rotary head carrying a plurality of pressing appliances, each possessing a pair of pressing plates which face each other. Through the agency of the rotary head, the pressing appliances, moving and stopping in turns, enter successive processing stations in which joint burn-in appliances are located, each comprising a pair of burn-in jaws which face each other. The pressure exerted on the pages of the books is maintained during the cyclic, start-stop movement of the books through the individual processing stations, and in each station the joint burn-in device is closed once per cycle, so as to form the book cover hinges and to subject these regions to the action of heat. The pressing appliances can be individually adjusted to suit books of different thicknesses, adjustment being performed by shifting the outer pressing plates over a set of surface serrations on the end portions of supporting rods.
In a further development of the above-described book shaping and pressing machine, the joint burn-in appliances are located on the pressing appliances, and are cycled onwards together with them, moving and stopping in turns. The joint burn-in jaws can consequently be kept closed during the rotary movement, thus making more time available for the heat to act on the cover material.
A machine of this more advanced design, called also a "joint burn-in and pressing machine", is described in an article in the periodical "Deutscher Drucker", No. 33/6-9-73, page 10, Cols. 3 and 4. In this article, emphasis is placed on the fact that it is particularly important, especially when working with heat-sensitive cover materials, for the machine to be capable of operating with the burn-in rails at a relatively low temperature, and this capability is guaranteed by the number of processing stations.
However, in a joint burn-in and pressing machine of the above-described generic type, the range of book through-put is severely restricted by the fixed number of individual stations that is decisively important as regards the quality of the books, in association with the necessarily intermittent mode of operation involving inter-station transport. Because of its lack of flexibility, the machine is not extendable, and an increase in the number of processing stations would mean a basically new machine, and this would be possible, if at all, only within very narrow limits, owing to the large inertia forces. In addition to this problem, there would also be a considerably greater requirement for non-utilizable floor area.
German Patent 1,804,644 discloses a book press with pressing and creasing stations that are arranged in a straight line. In this book press, the pressing and creasing stations are installed in two parallel channels or passages, so as to increase production. In addition, a conveying system, situated between the pressing plates and the creasing tools, continuously holds the books in a clamped condition while each is pressed and the creases are impressed into it. Through the agency of actuating arrangements, the pressing plates and creasing tools can be moved in order that their displacement relative to one another at particular times is such that they bear against the side surfaces of the books, and against those areas of the books which are to be shaped. The transport system of the apparatus of German Patent 1,804,644 performs a pressing operation on those areas of the books not gripped by the pressing plates. In applications involving book covers with delicate surfacing materials, and especially in cases involving lacquered or cellophane-surfaced covers, there is no way of suppressing markings in the transition zone between the transport system rails and the pressing plates.
The operations in which the books, leaving an upline machine in a single stream, are transferred into the twin-channel arrangement, and in which they are subsequently spaced one from another and introduced into a downline machine, necessitate the use of additional conveying systems, which are expensive to construct.
Moreover, in the straight-line twin-channel configuration, the book press can be utilized only for a restricted range of outputs. One the one hand, this disadvantage is inherent in the start-stop mode of operation, necessarily involving inter-station transport, and while in theory there is no limit to the number of processing stations, increasing the number of stations would entail a floor area requirement that could not be justified.